Live Video: Twin NASA probes to crash into moon Monday

Two NASA probes are set to crash into a northern mountain on the moon Monday afternoon, although observers from Earth won't be able to to see it.

The crashes will be at 2:28 p.m. at an unnamed mountain near the moon's north pole. The mountain is on the moon's near side, but it will be in shadow at the time of impact.

Jet Propulsion Laboratory, which manages the mission, will provide live online commentary from mission control at www.nasa.gov/ntv.

The probes, named Ebb and Flow, spent the past year mapping the moon's gravity for the Gravity Recovery and Interior Laboratory mission.

The mission required the probes to maintain low orbits over the moon's surface, and they are now being sent purposely into the moon because they do not have enough altitude or fuel to continue science operations.

They are now on a trajectory to crash into the mountain at 3,760 mph, when the mountain rises higher than their orbital altitude.

Friday also marked the 40th anniversary of the last time humans stepped foot on the moon, during Apollo 17,and GRAIL mission managers took steps to avoid disturbing historic sites.

"NASA wanted to rule out any possibility of our twins hitting the surface anywhere near any of the historic lunar exploration sites like the Apollo landing sites or where the Russian Luna probes touched down," said David Lehman, GRAIL project manager at JPL. "Our navigators calculated the odds before this maneuver as about seven in a million. Now, after these two successful rocket firings, there is zero chance."